Method and/or system for transferring/receiving audio and/or video signals and minimizing delay time over internet networks and relating apparatuses

ABSTRACT

A method and system for transferring/receiving audio and/or video signals and minimizing delay time over Internet networks including, in transmission, converting, analog audio and/or video input signal to digital form by means of an A/D converter, processing the digital audio and/or video signal in order to manipulate, control, adapt or change it, converting the sampling rate of the digital audio and/or video signal for adapting the digital input clock to the network clock or for adapting the A/D clock to the network clock resulting in an clock-adapted digital signal, encoding the clock-adapted digital signal for reducing the number of bits resulting in a lower bit rate encoded signal, multiplexing the encoded signal and packing it into a resulting multiplexed signal which needs to comply with the used and/or applied network interface, inserting the multiplexed signal into a network, and analysing the active network interface for deterimining the network interface that is receiving and/or sending data; and in reception, analysing the active network interface for determining the network interface that is receiving and/or sending data, applying the multiplexed signal from the network to a bitstream analyser, de-multiplexing the signal for obtaining an encoded signal, decoding the encoded signal into a digital audio and/or video signal, converting the sampling rate of the digital audio and/or video signal for adapting the network clock to the digital output clock or to adapt the network clock to the D/A converter clock and resulting in a clock-adapted digital signal, processing the clock-adapted digital signal, and converting the digital audio and/or video signal into analog form by means of an D/A converter.

The present invention refers to a method and/or system for transferringaudio and/or video signals and minimizing delay time over Internetnetworks.

It is known that Internet network is used for transferring several kindsof information among which also audio and/or video signals.

Today the transmission of audio as well as video signals via theInternet is known as being very slow, delayed and un-reliable.

E.g. web radio is not matching the quality of today broadcast listenersin FM or Digital Radio services. The overall delay in web radio sometimes can be higher than several seconds. Furthermore the audio qualityis depending on the available network capacity. If too many users areusing the Internet, the audio signal transfer may be interrupted.

Due to such results, professional audio and video broadcasting does notuse IP (Internet Protocol) network for professional applications, inparticular it avoids to use IP for live transmissions.

Aim of the present invention is to overcome the above describeddrawbacks and improving the quality of the transfer of audio and videosignals over IP network by minimizing delay time and reducing thebandwidth requested.

For achieving such aims the present invention has as its object a methodand apparatuses for transferring audio and/or video signals andminimizing delay time over Internet networks, having the distinctivefeatures described in claim 1 and further defined by sub-claims.

Further aims and advantages of said invention will result in beingclearer from the detailed description that follows and annexed drawingsupplied as an explicative and non-limiting example.

Only for practical reasons, the example described refers to a method oftransmission and reception of audio signals over Internet Protocolnetworks but the same principles are applicable also to video signals.

FIG. 1 represents a block diagram of a transmission and receiving systemof audio signals according to the invention.

The system consists of the following parts which may be set in sequenceor in another order to define certain applications, where,

on transmitting side:

With number 1 is indicated an analog audio input signal, mono or stereo,

With 2 is indicated an A/D converter converting the analog signal into adigital signal when analog inputs are used;

With 3 is indicated a digital audio input signal, mono or stereo ormulti-channel 5.1, or 7.1 or similar, which is the result of the A/Dconversion or a direct digital input; when digital inputs are used theA/D converter 2 is not used;

With 4 is indicated an audio processing unit able to manipulate,control, adapt or change the digital audio signal;

With 5 is indicated a sampling rate converter needed for adapting thedigital input clock to the network clock or for adapting the A/D clockto the network clock resulting in an clock-adapted digital signal;

With 6 is indicated an Encoder(s) to encode the digital signal, forinstance, into a linear, perceptual-coded or non-perceptual-coded formatfor reducing the number of bits resulting in a lower bit rate encodedsignal; the choice of the coding algorithm and the setting of someparameters, such as frame length, bit rate and sampling rate, etc., isperformed with the aim to reduce the delay time of the transmission overIP networks;

With 7 is indicated a data inserter which may be used to insertadditional data, either within the encoded signal or in a separatedstream; alternatively the data inserter may be used to replace lesssignificant bits of the encoded signal with such additional data (i.e.in the way described in German patent application DE 44 30 864);

With 8 is indicated a bitstream generator to multiplex the encodedsignals and/or data signals and/or the hidden data signals and to packthem into a resulting multiplexed signal which needs to comply with theused and/or applied network interface; the obtained packet data shall beopportunely sized so that the delay time in the transmission is reduced;

With 9 is indicated a network interface which puts the multiplexedsignals in the network;

With 10 is indicated a network analyser which analyses the activenetwork interface or verifies which network interface is receivingand/or sending data;

on receiving side:

With 11 is indicated a network analyser which analyses the activenetwork interface or verifies which network interface is receivingand/or sending data;

With 12 is indicated a network interface which takes the multiplexedsignal from the network and provides it to a bitstream analyser 13;

With 13 is indicated the bitstream analyser which analyses themultiplexed signal in order to de-multiplex the signal for obtaining anencoded signal;

With 14 is indicated a Decoder(s) to decode the encoded signal into adigital signal; said decoder shall be able to decode the same codingscheme used in the transmitting side, for instance a linear,perceptual-coded or non-perceptual-coded format;

With 15 is indicated a sampling rate converter needed for adapting thenetwork clock to the digital output clock or to adapt the network clockto the D/A converter clock and resulting in a clock-adapted digitalsignal;

With 16 is indicated an audio processing unit able to manipulate,control, adapt or change the digital audio signal;

With 17 is indicated a digital audio output signal, mono or stereo ormulti-channel 5.1, or 7.1 or similar, which results the replica of thedigital audio input signal 3;

With 18 is indicated a D/A converter converting the digital audio signalinto a analog audio signal;

With 19 is indicated an analog audio output signal, mono or stereo,which results the replica of the analog audio input signal 1.

The characteristics of the described methods, object of the presentinvention, result clear from the present description and annexeddrawing.

The advantages of the method object of the present invention also becomeclearer from the description.

They consist in the fact that from the encoding part of the system theencoded signal and/or data signal and/or the hidden data signal arepacked by the bitstream generator into IP datagrams, which constitutethe above said multiplexed signal encoded with the aim to reduce thedelay time of the transmission over IP networks. An IP datagram alwaysincludes an header, with synchronization, delivering and systeminformation, which represents an overhead. Said overhead being higherwhen more-significant short packets are used or transmitted and beinglower when less-significant longer packets are used or transmitted.

In particular, the IP packet generated by the bitstream generator 8 isoptimised by minimizing the packet size for the TCP (transfer controlprotocol) or UDP (user datagram protocol) packages.

Further advantages are represented by determined choices carried outinside the encoder 6. For instance, low delay coding algorithm may bechosen or other parameters may be set with the aim to reduce the delaytime, namely a small frame length, an high bit rate and an high samplingrate.

Such parameter setting allows the user to control the coding delay timeversus quality and bit rate and similar parameters and can include anautomatic calculation to reach lowest delay or lowest bandwidth. This isconsidered to be a great benefit.

The same situation is obtained in the receiving part of the system withthe use of devices that are mirroring the encoding/transmitting part.

It also clear that numerous variants can be supplied by the skilled manto the method and/or system for transferring/receiving audio and/orvideo signals and minimizing delay time over Internet networks andrelating apparatuses described as an example, without however departingfrom the novelty principles inherent in the present invention.

1. Method for transferring/receiving audio and/or video signals andminimizing delay time over Internet networks comprising the steps of: Onthe transmitting side: Converting, if available in analog form, audioand/or video input signal in digital form by means of an A/D converter;processing the digital audio and/or video signal in order to manipulate,control, adapt or change it; converting the sampling rate of the digitalaudio and/or video signal for adapting the digital input clock to thenetwork clock or for adapting the A/D clock to the network clockresulting in an clock-adapted digital signal; encoding the clock-adapteddigital signal for reducing the number of bits resulting in a lower bitrate encoded signal; multiplexing the encoded signal and packing it intoa resulting multiplexed signal which needs to comply with the usedand/or applied network interface; putting the multiplexed signal in anetwork; analysing the active network interface or verifies whichnetwork interface is receiving and/or sending data; on the receptionside: analysing the active network interface or verifying which networkinterface is receiving and/or sending data; taking the multiplexedsignal from the network and providing it to a bitstream analyser;analysing the multiplexed signal in order to de-multiplex the signal forobtaining an encoded signal; decoding the encoded signal into a digitalaudio and/or video signal; converting the sampling rate of the digitalaudio and/or video signal for adapting the network clock to the digitaloutput clock or to adapt the network clock to the D/A converter clockand resulting in a clock-adapted digital signal; processing theclock-adapted digital signal to manipulate, control, adapt or change it;converting in analog form the digital audio and/or video signal by meansof an D/A converter; in which, for reducing the delay time of thedigital audio and/or video signal transfer, the IP packets generated bybitstream generating means are optimised by minimizing the packet sizeand low delay coding algorithm are chosen by encoding means, wherein,the setting of one or more parameter as frame length, bit rate andsampling rate allow the user to control the coding delay time versusquality and bit rate.
 2. Method for transferring/receiving audio and/orvideo signals according to claim 1, wherein a data inserter is used toinsert additional data, either within the encoded signal or in aseparated stream, or, alternatively, used to replace less significantbits of the encoded signal with such additional data;
 3. Apparatus forthe transmission of audio and/or video signals and minimizing delay timeover Internet networks comprising means for converting audio and/orvideo input signal in digital form by means of an A/D converter; meansfor processing the digital audio and/or video signal in order tomanipulate, control, adapt or change it; means for converting thesampling rate of the digital audio and/or video signal for adapting thedigital input clock to the network clock or for adapting the A/D clockto the network clock resulting in an clock-adapted digital signal; meansfor encoding the clock-adapted digital signal for reducing the number ofbits resulting in a lower bit rate encoded signal; means formultiplexing the encoded signal and packing it into a resultingmultiplexed signal which needs to comply with the used and/or appliednetwork interface; means for putting the multiplexed signal in anetwork; and means for analysing the active network interface orverifies which network interface is receiving and/or sending data. 4.Apparatus for the reception of audio and/or video signals and minimizingdelay time over Internet networks comprising means for analysing theactive network interface or verifying which network interface isreceiving and/or sending data; means for taking the multiplexed signalfrom the network and providing it to a bitstream analyser; means foranalysing the multiplexed signal in order to de-multiplex the signal forobtaining an encoded signal; means for decoding the encoded signal intoa digital audio and/or video signal; means for converting the samplingrate of the digital audio and/or video signal for adapting the networkclock to the digital output clock or to adapt the network clock to theD/A converter clock and resulting in a clock-adapted digital signal;means for processing the clock-adapted digital signal to manipulate,control, adapt or change it; and means for converting in analog form thedigital audio and/or video signal by means of an D/A converter. 5.System for transferring/receiving audio and/or video signals andminimizing delay time over Internet networks comprising means forconverting audio and/or video input signal in digital form by means ofan A/D converter; means for processing the digital audio and/or videosignal in order to manipulate, control, adapt or change it; means forconverting the sampling rate of the digital audio and/or video signalfor adapting the digital input clock to the network clock or foradapting the A/D clock to the network clock resulting in anclock-adapted digital signal; means for encoding the clock-adapteddigital signal for reducing the number of bits resulting in a lower bitrate encoded signal; means for multiplexing the encoded signal andpacking it into a resulting multiplexed signal which needs to complywith the used and/or applied network interface; means for putting themultiplexed signal in a network; means for analysing the active networkinterface or verifies which network interface is receiving and/orsending data; means for analysing the active network interface orverifying which network interface is receiving and/or sending data;means for taking the multiplexed signal from the network and providingit to a bitstream analyser; means for analysing the multiplexed signalin order to de-multiplex the signal for obtaining an encoded signal;means for decoding the encoded signal into a digital audio and/or videosignal; means for converting the sampling rate of the digital audioand/or video signal for adapting the network clock to the digital outputclock or to adapt the network clock to the D/A converter clock andresulting in a clock-adapted digital signal; means for processing theclock-adapted digital signal to manipulate, control, adapt or change it;and means for converting in analog form the digital audio and/or videosignal by means of an D/A converter.
 6. A method according to claim 1wherein the encoded signal is obtained by a low delay coding algorithmand is coded with frame length, high bit rate and an high sampling rate.7. A method according to claim 1 wherein the multiplexed signal isassociated with an IP packet that has the minimum packet size.
 8. Amethod according to claim 1 wherein the decoded signal is obtained bydecoding a low delay algorithm and a small frame length, an high bitrate and an high sampling rate.
 9. A method according to claim 1 whereindemultiplexed signal is associated with an IP packet that has theminimum packet size.